W. Hopkins on Changes of Climate. 81 
stream. I shall consider hereafter the manner in which this great 
current may have been arrested, or diverted from its present course. 
In discussing the positions of the isothermal lines for the north- 
ern hemisphere in this case, we may again commence with the 
January line of 32°F. 'There appears no cause for any material 
alteration in its position in southern Asia east of the meridian of 
about the 70th degree of longitude. 'To the west of that meri- 
and probably somewhat more than I have supposed it to be 
ia by the Atlantic, independently of the effect of the Gulf 
Strea 
tn the region of North America the isothermal would depend on 
tie manner in which the Gulf-stream should be diverted from its 
Present course. The neighboring isothermals would follow the 
~ “tse of that of 32° with approximate parallelism. The July 
‘sothermals, which should traverse the sea that we are now sup- 
Pesing to extend nearly as far east as the Ural Mountains, would 
be deflected southward as they are at present on approaching the 
shores of western Europe. It will be observed that the July iso- 
thermal of 63¢-5 intersects the January one of 32° (as I have drawn 
“em for the case previously considered of the absence of the Gulf- 
Stream ) at a point very near the extreme western coast of Brittany 
($ U1, P- 74.) Between this point and the meridian of the Ural 
July tains, the January line would lie more to the north and the 
“Y Ohe more to the south, by the influence of the extended 
ocean. The effect, therefore, would be to equalize in a greater 
me than at present the summer and winter temperatures of 
eased In the Vicinity of the European portions of these lines, 
Sly without producing any material changes in its mean 
Senus, Vol. XV, No, 43—Jan., 1853. 11 
